Captive air bubble air replenishment process



oct. 14, 1969 H- J4 BERNJERTS 3,472,193

CAPTIVE AIR BUBBLE AIR REPLENISHMENT PROCESS Filed Feb. 26, 1968ATTORNEY! United States Patent O 3,472,193 CAPTIVE AIR BUBBLE AIRREPLENISHMENT v PROCESS Henry J. Bernaerts, 900 Primrose Road, Apt. 203,Annapolis, Md. 21403 Filed Feb. 26, 1968, Ser. No. 708,214 Int. Cl.B631) 1/38 U.S. Cl. 114-67 10 Claims ABSTRACT OF THE DISCLOSURE Asurface effect vehicle having side skirts or walls such as captured airbubble vehicle or the like is provided with submerged, movable vehiclepropelling thrusters located forwardly of the bubble so that theirexhausts may be directed to portions of the vehicle to enhance the sidewall seal and to replenish air in the bubble.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

Background and summary In higher sea states a surface effect vehiclesuch as a captured air bubble vehicle tends to lose its air sealing atits side walls or skegs. Wave activity exposes the bottom extremities ofthe skegs past which air may escape. The purpose of this invention is toprovide an arrangement whereby there is related to the vehicleconfiguration vehicle-propelling streams of water which may have gasentrained therein. These vehicle-propelling streams are produced bythrusters and are directed toward the vehicle side walls and/or towardthe forward portion of the air cushion. In this arrangement the streamof water enhances the bubble seal and provides air for replenishing thebubble by employing wake effects of the advantageously positionedthrusters.

Brief `description of the drawings For a better understanding of theinvention, reference is made to the accompanying drawings in which likenumerals represent like parts and in which:

FIGS. 1 and 2 are respective side elevation and plan views ofvehicle/propulsion arrangement according to one version of theinvention, and

FIG. 3 is a view in side elevation for further describing the inventionand its operation.

Detailed description and operation Referring to FIGS. 1 and 2, a surfaceeffect vehicle illustrated as a captured air bubble vehicle 11 ofconfiguration similar to that shown in U.S. Patent No. 3,- 146,752issued to A. G. Ford, has respective fore and aft end walls or curtains13 and 15, port and starboard side walls or skegs 17 and 19, and acaptured air bubble 21. Two water states and levels are represented atrelatively low sea states by solid line 23 and at higher sea States bybroken line 25 in relation to the vehicle 11.

At the forward end of vehicle 11 is a vehicle body portion 27 extendingforwardly of the curtain 13. Extending downwardly, forwardly andoutwardly from body portion 27 are respective port and starboard fairedstruts 29 and 31 of rigid construction and firmly attached in anysuitable well known manner to the vehicle 11. The exact point ofattachment of the struts is not critical as long as their lowerniostextensions are forward of the curtain 13 and outboard of the skegs.Preferably, the lowermost extensions are below the bottom surfaces ofthe skegs.

3,472,193 Patented Oct. 14, 1969 ice Each of the struts 29, 31 may be ofhollow, framed construction covered by any suitable strong skinmaterial. At the bottom of the respective struts are respectiverotatably mounted thrusters or propulsion units 33, 35. The thrusterunits 33, 35 may be identical and may be of any suitable designconfiguration capable of producing a water stream with or without gasentrained therein. For example, the thrusters may be high speedpropellers, Kort nozzles, pump jets or, preferably, water ramjets of thetype known commercially as Marjets manufactured by the Martin MariettaCo. Marjets are well known in the art and are not discussed in detail.Essentially, a Marjet is an axial flow ramjet having aperture means forintroducing into the iiow air or gas at high pressure to produce a highvelocity exhaust of water entrained air.

As shown in FIGS. 1-3, the propulsion units 33, 35 are one or morethrusters mounted at the bottom of each strut for rotation about an axisparallel to the intersection line of the transverse plane and thelongitudinal plane of symmetry of the vehicle. Fluid such as air at highpressure may be introduced to each thruster via conduits 37, 39,respectively, in the struts.

A source of high pressure fluid, such as gas or air, is indicated at 41,it being understood that such source may be of any suitable well knowndesign, e.g., axial or centrifugal compressor, rocket, air-ramjet, andthe like. A valve control switch 43 may be provided for the source 41 inorder to selectively supply air or gas to the thrusters. Of cou-rse,because the thrusters 33, 365 are rotatable, a rotary seal coupling eachof the conduits 37, 39 to the respective thrusters may be employed. Suchseal may be of any suitable Well known design.

Any suitable well known means, not shown, may be employed to steer orrotate the respective thrusters. For example, hydraulically actuated andcontrolled pistons may rotate a gear coupled to the thruster; or a wormgear rotated by electrical or pneumatic motors may be coupled to a gearmeans rotating each thruster.

In operation, as best shown in FIGS. 2 and 3, when each thruster is in aposition A parallel to the fore-aft axis of the vehicle, the propulsionefficiency for the vehicle is at a maximum. Further, because of the wakeeffect of each thruster, there is advantageously present a wave effectacting on the outer surfaces of skegs 17 and 19 against the waveproducing action of the skegs themselves. This action tends to providegreater amounts of water of high kinetic energy for providing `a seal atthe vicinity of the skeg bottoms than would otherwise be the case. Thehigh kinetic energy water stream tends to break down the preexistingwave amplitudes at the skeg surfaces so that wave pattern 25 is reducedto a pattern 23.

When rotatable thrusters 33, 35 are in their B positions, as indicatedin FIG. 2, additional volumes of water are directed against the outersurfaces of the skegs. In the B position, the thrust eiciency of thethrusters is decreased somewhat in favor of producing additionalthrusted exhaust water and air entrained therein which provides at theouter surfaces of the skegs water ow which diminishes the elfect ofambient wave action to a degree greater than when the thrusters are inposition A. As shown in FIG. 3, ambient waves 25 are diminished inamplitude at the vicinity of the outer surfaces of the skegs so as toform lower amplitude waves 23.

When the thrusters are at position C, thruster exhaust is directedtowards the forward curtain 13. Because the thruster exhaust may containboth water and air entrained therein, the air supply of the cushion 21is replenished. Mode C is particularly advantageous for providing bubblestability at high sea states.

Obviously, thruster positions intermediate A', B, and C, may be selectedso that the individual effects of these positions are combined. Forexample, assuming the thrusters produce air entrained water streams, athruster position between A and B provides slightly less propulsionefficiency and greater water supply at the outer surfaces of the skegsthan at position A. A thruster position intermediate B and C provides apredetermined ratio of effects between that of position B and the airreplenishment mode of position C.

It is to be understood that while the version of the invention has beendescribed in relation to a captured air bubble type of vehicle, theprinciples of the invention apply to any surface effect vehicleemploying side skirts, i.e., hydroskimmers, Hovercraft, and the like.

While the version of the invention shown is directed toward positioningthrusters outboard of the skegs, it is realized that advantages similarto those already described herein are obtained by placement of thethrusters at positions forward of the curtain 13 and inboard of theskegs. With inboard placement of the thrusters 33, 35, the supply of airin the cushion will be replenished in all directional modes of thethrusters, while boundary condition control at the junction of skegs andwater will occur in conjunction with air replenishment when thethrusters are turned outwardly from direct fore and aft alignment.

Each of the thrusters 33, 35 may comprise a pump producing a highkinetic energy water stream without appreciable entrained gas to carryout the objectives of the A and B modes. Alternatively, each of thethrusters may comprise means to produce air entrained water streams ofhigh kinetic energy to accomplish the objectives of all three modes, A,B and C. If desired, each thruster may comprise means such as control 43to produce selectively a water stream with or without entrained gas orair. For example, an axial ow water pump may have valve controlled airinjecting means whereby air may be selectively injected into the waterflow downstream of the pump compressor.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. The method of controlling the effects of varying sea states on asurface effect vehicle having a supporting air cushion at leastpartially confined by water surface piercing, longitudinal side wallscomprising the step of:

directing a vehicle-propelling stream of water against the forwardportion of a surface of at least one of said side walls to enhance theseal between said air cushion and said side walls.

2. The method of controlling the effects of varying sea states on asurface effect vehicle having a supporting air cushion at leastpartially confined by water surface piercing, longitudinal side wallscomprising the step of:

directing a vehicle-propelling stream of water having gas entrainedtherein toward the forward portion of the air cushion to replenish theair in said air cushion.

3. The method of controlling the effects of varying sea states on asurface effect vehicle having a supporting air cushion at leastpartially confined by water surface piercing, longitudinal side wallscomprising the step of:

directing a vehicle-propelling stream of water having gas entrainedtherein both against the forward portion of a surface of at least one ofsaid side walls to enhance the seal between said air cushion and saidside walls and toward the forward portion of the air cushion toreplenish the air in said air cushion.

4. For a surface effect vehicle having at least two water surfacepiercing, longitudinal side walls at least partially confining avehicle-supporting cushion of air, means for propelling the vehicle andfor enhancing the seal between the air cushion and the side walls, saidmeans comprising:

submerged vehicle-propelling thruster means located essentiallyforwardly of the submerged body outline of said vehicle, said thrustermeans producing output propulsion products including a water stream ofhigh kinetic energy; and

strut means for attaching said thruster means to said vehicle wherebythe output of the thruster means is adapted to be directed aftwardly andin a direction against at least a portion of the plan outline of thevehicle.

5. Apparatus according to claim 4 wherein said thruster means comprisesa port and a starboard thruster element.

6. Apparatus according to claim 5 wherein said strut means comprises arespective strut member for each said thruster element.

7. Apparatus according to claim 5 wherein each of said thruster elementsis mounted for rotation about an axis essentially parallel to theintersectional line of the transverse plane and the longitudinal planeof symmetry of the vehicle.

8. Apparatus according to claim 5 wherein each of said thruster elementsis positioned outboard of the side walls of the vehicle.

9. Apparatus according to claim 4 including means for supplying gasunder pressure to said thruster means, whereby the output propulsionproducts of said thruster means include gas entrained therein to therebyenable replenishment of the air cushion.

10. For a surface effect vehicle having at least two water surfacepiercing, longitudinal side walls at least partially confining avehicle-supporting cushion of air, means for propelling the vehicle, forenhancing the sealing of the air cushion, and for replenishing the airin said air cushion, said means comprising:

a port and a starboard vehicle-propelling thruster essentiallysubmerged, each thruster being located essentially forwardly of thesubmerged body outline of the vehicle;

strut means attaching each thruster to said vehicle, each of saidthrusters being rotatably mounted on said strut means;

a source of gas for each of said thrusters; and

means connectively associated with said source of gas for selectivelysupplying said gas to said thrusters whereby the thrusters produce Waterstreams with or Without gas entrained therein.

References Cited FOREIGN PATENTS 19,451 6/1904 Austria. 1,129,834 5/1962Germany.

ANDREW H. FARRELL, Primary Examiner

